The objectives of this pilot project are to evaluate changes in ovarian morphology, serum estrogen, bone density, and DNA deletions over time in female rhesus monkeys. Preliminary results indicate that bone strength from young monkeys 3-5 years of age and aged monkeys 22-25 years is different and that breaking strength of femurs decreases substantially with age. Young monkey femur strength was 13.5 MPa (comparable to a previous report by Yamada, 1970) while aged monkey femur strength averaged 9.7 MPa, about 70% less. Thickness of cortical and trabecular bone decrease with age while the number of trabecular intersections increases. Similar measurements using the wing of the pelvis (iliem) failed to demonstrate these correlations. Enumeration of eggs, primary follicles and cystic follicles in histologic sections of ovaries showed substantial decreases with age. We have recently expanded this study to test strength of femurs and lumbar vertebrae in a large number of specimens from animals ranging from 1-29 years. The results could provide the basis for future studies on effects of aging in females from puberty through menopause in response to exercise and dietary